The Neural Prosthesis Program of the National Institute of Neurological Disorders and Stroke is committed to research and development on functional neuromuscular stimulation (FNS) to restore hand and arm function in quadriplegic individuals at the highest functional level possible. These FNS systems operate under the voluntary control of the individual. Generating control signals for a prosthesis that are integrated with the individuals uninjured, voluntary, cortical motor system is a critical part of any potential FNS system. Presently, control signals are generated by voluntary movements of unparalyzed muscles such as the contralateral shoulder. The goal of this research is to establish the feasibility of generating control signals by direct voluntary control of neurons in the central nervous system (CNS). To demonstrate that cortical neural activity can be used to control a prosthesis, we need to demonstrate that the neural activity of selected cell populations in the CNS can be reliably recorded for extended periods of time. Then it must be shown that the signals from this population of neurons can, under voluntary control, reliably control an electromechanical device. During the current contract period, it has been demonstrated that a rat can modulate neural activity in its motor cortex to control a mechanical arm to retrieve a food reward. Efforts are underway to duplicate these results in animals with a gyrencephalic brain, but thus far, chronic recording has been difficult to achieve in larger brained animals. The focus of this research will be on the development of chronic microelectrode recording techniques in a primate with a gyrencephalic brain. There will also be research on extracting control signals from the recorded neural activity.